ok, as a health geek, I'll add a couple of things. Someone earlier said early humans didn't eat much meat. I don't know that I would go along with that. We are adept hunters & it's reasonable to think humans were quite successful at trapping stuff, or herding it off cliffs. And while they probably did gorge, I will also disagree with something said, that they gorged because they didn't have any way to preserve the meat. Of all the foods in nature, meat is one of the easiest to preserve. Just cut it into strips & dry it. The protein makes it hard & long-lasting.

As for good fat/bad fat, keep in mind that wild animals have much less body fat than today's farmed animals. And further, that it was better, in that it contained more nutrients & certainly less toxins. Also, as someone else pointed out, humans didn't have to live all that long. Start your family at 15, & you could die at 30 having raised a child to a useful reproductive age.

The idea of doing what's natural, doing what we evolved with, that's very tricky. We evolved being very physically active. Good. We also evolved dying from malaria. Bad. For a while I was reading about the whole raw food diet. And while I could never confirm the whole 'does cooking kill the enzymes' thing & does it matter, the truth is I do feel much better when I eat a mostly raw diet. But you have to break that down. Is it because the food is raw, or because following a raw diet causes you to eat unprocessed food with the fiber intact? In other words, could you be just as healthy on whole cooked food? And anyway the whole idea behind raw eating, that it's natural, that humans evolved eating raw, is weak. We have used fire for at least 10,000 years & there is every evidence that has affected our bodies & culture. Also, if you look at raw food recipe books, they lean heavily on nuts & fresh greens. Be real. Unless you came from some tropical island, there is no way your north european ancestors had fresh greens all winter. Much less the raw food standby of almonds. Or coconuts.

I think it is absolutely wise & useful to look back at how we lived when we were successful at surviving long enough to evolve. But there is no way you can live that life in any kind of pure way. And we can only speculate at what ancient people may have eaten. Their lives are so far removed from our casserole potlucks; we are utterly amputated from the land & the seasons.

I think it's futile to get caught up in trying to replicate a diet you don't even know existed. Heck, there are tons of fruits, berries, & plants that have gone extinct in the last 10,000 years. Instead, use the advantages you have in modern life. No, drinking almond milk wasn't how my ancestors evolved, but it makes me feel healthy & they have organic almonds just down the road at the co-op. I can research & imagine the diet of a healthy human in touch with nature, then I can go beyond it. Antioxidants in blueberries? Fine. I don't have to wait for July, I can buy them frozen & have them all year.

I was born and raised in small town Oregon where the way to get around was by car. I rode my bike as a kid, drove as a teenager, and was fed a lot of packaged food.

I went to Russia for a year after high school. I was fed potatoes, fish, some pathetically thin chicken breasts, and a lot of beets and cabbage, rye bread, kasha, etc Lots of carbs! However, the food was all fresh and either made locally, or grown by the family I lived with. Most families grew a large portion of their food. At the time, a lot of packaged foods like condiments and pasta had no added sodium or sugar or chemicals. Candy and soda were once in awhile treats. Once in awhile as in...maybe weekly at most. (It might be different these days) I also had to walk everywhere.

In seven months I lost 40 pounds, my skin cleared up, and I felt clear headed.

I think that the American lifestyle is what's killing us. One single diet isn't going to fix you. It's a change in your lifestyle that will. I have to agree with others...eating fresh and local food (the less processed the better), and daily activity is the best way to go. While I tend to agree with the OP about the Paleo community being a little too alarmist, the basic idea of eating fresh and simple and moving is sound.

We make our world significant by the courage of our questions and the depth of our answers.